There is only one valid node on the bus: the node that sends the packet will detect the status of the reply gap on the bus after sending a frame. If the reply gap is detected as a hidden bit, it means that the frame has not received an ACK, the transmission fails, and the need to resend it. The sending error counter will be added up after the transmission fails until the node is closed. Therefore, when there is only one valid node on the bus, this node cannot send out data, because the ACK Slot in the data frame it sends out is not filled by another node, and will always be a hidden bit, and this node will continue to resend data until the transmission is successful or the transmission is canceled.
The baud rate does not match or the node is not initialized, resulting in no ACK.
Bus cable short circuit, open, reverse connection;
The nodes connected to the high-speed CAN bus are not high-speed CAN, but fault-tolerant low-speed CAN, resulting in mismatches.